Erythromelalgia is a fairly rare disorder manifested by vasodilatation of the blood vessels in the feet. Normally blood flow through the feet and hands is regulated by nerves and muscles in the walls of the blood vessels that either tighten and shrink the vessel's diameter so as to restrict flow or to open the blood vessels diameter to allow for more flow. This is all controlled automatically by the body and is necessary to preserve or give up body heat so that we maintain a constant body temperature.
For instance, when we are subjected to cold temperatures the blood vessels will constrict and shunt blood back to the heart and body cavity. This is an example of how our body responds to cold and is a survival mechanism to keep us alive if we where exposed to prolonged or severely cold temperatures. The heat of the blood is not allowed to escape in the fingers and toes into the air or water around us and is sent back to the heart to keep the core body temperature warm so your heart will continue to beat. Certainly you have heard "Cold hands, warm heart". When we are hot just the opposite happens and the blood vessels enlarge or dilate allowing for more blood to go to the fingers and toes thereby 'giving up heat' to the surrounding air. The 'cooler blood then goes back to the heart where it helps lower core temperature.
The vasoconstriction (tightening of the blood vessels) and the vasodilatation (opening of the blood vessels) is always changing and adjusting to maintain blood pressure, control body heat, regulate heart rate, among other functions you don't even think about. Part of the controls for this are partially understood and maintained by the primitive part of our nervous system called the autonomic nervous system. It is this part of our nervous system that is responsible for out heart to beat and for us to breath regularly without having to think about it.
When these controls fail to operate normally we see the pathologic disease patterns of erythromelalgia or Raynauds disease or phenomenon. Raynauds disease or phenomenon is a vasoconstriction of the blood vessels in the feet and hands. We notice it when our fingers and toes get icy cold and turn blue or even white. This can be a very painful condition depending on how long we are subjected to the cold and the vasoconstriction since the tissues of the hands or feet are deprived of blood and therefore oxygen. In many individuals it may be very mild and not be a problem. All of us experience vasoconstriction to some degree when we are in cold weather. In the disease state however the vasoconstriction does not entirely reverse when subjected to warmer temperatures and a chronic painful situation ensues.
Erythromelalgia on the other hand is just the opposite. The blood vessels are open or dilated and the oxygen and heat of the blood is discharged into the tissues making them turn red and feel hot all the time. Likewise this can be a very painful condition. It is a more rare disorder and less understood than Raynauds.
Before treatment, the diagnosis should be confirmed. This can be accomplished by a variety of different medical specialties. Internal medicine or an internist is a good place to start to make sure there are no disease factors or other medications causing the Raynauds or erythromelalgia. In many instances the internist will treat the disorder so he may help you monitor medications that have undeliverable side effects or react with other medications.
These disease states can be treated with varying degrees of success using drugs that induce vasodilatation or vasoconstriction. Unfortunately, the side effects of vasodilators or vasoconstrictors are often times worse than the disease. Obviously, avoiding temperatures or situations that can trigger the responses are also useful. For instance, people with vasoconstrictive problems should wear socks and well insulated shoes to maintain heat. Patients with vasodilatation problems may be more comfortable in sandals, going barefoot, or certainly using a light shoe that can 'breath' to allow heat to escape. In severe conditions pain medications can be a useful adjunct. Hypnosis and biofeedback may have some degree of success in certain individuals if administered by appropriately trained individuals.